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https://www.readbyqxmd.com/read/29334589/preparation-and-evaluation-of-a-deoxycholic-calix-4-arene-hybrid-type-receptor-as-a-chiral-stationary-phase-for-hplc
#1
Sadegh Yaghoubnejad, Kourosh Tabar Heydar, Seyyed Hamid Ahmadi, Reza Zadmard, Nima Ghonouei
We report the synthesis and enantioseparation characteristics of two novel covalently immobilized deoxycholic acid derivatives as chiral stationary phases for high-performance liquid chromatography. In the structure of the first stationary phase, the 3-position of deoxycholic acid is substituted with a 3,5-dinitrophenylcarbamoyl group and the second one has an additional calix[4]arene attached to the carboxylic group of the deoxycholic acid. The chromatographic performance of the stationary phases was evaluated with enantioseparation of N-(3,5-dinitrobenzoyl)-dl-leucine, N-(3,5-dinitrobenzoyl)-dl-valine, omeprazole, diclofop-methyl, dl-mandelic acid and (RS)-pregabalin...
January 15, 2018: Journal of Separation Science
https://www.readbyqxmd.com/read/29334386/organic-inorganic-hybrids-having-a-talc-like-structure-as-suitable-hosts-to-guest-a-wide-range-of-species
#2
J Brendlé
The sol-gel process involving hydrolysis and condensation reactions is an attractive way to form siloxane based hybrid materials since it is a one-step method performed under mild conditions. Organic-inorganic hybrids having a talc-like structure (TLH) can be obtained using this procedure starting from organotrialkoxysilanes having the formula R-Si(OR')3 (where R stands for an organic moiety and R' for a methyl or ethyl group) with different functionalities, an aqueous or ethanolic solution of a magnesium salt, and in some cases, an aqueous solution of sodium hydroxide...
January 15, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/29334109/a-multifunctional-supramolecular-hydrogel-preparation-properties-and-molecular-assembly
#3
Lin Wang, Xuefeng Shi, Yaqian Wu, Jian Zhang, Yuejun Zhu, Jinben Wang
A novel supramolecular hydrogel was designed and constructed by molecular self-assembly of a cationic gemini surfactant, 1,3-bis(N,N-dimethyl-N-cetylammonium)-2-propylacrylate dibromide (AGC16), and an anionic aromatic compound, trisodium 1,3,6-naphthalenetrisulfonate (NTS). Owing to its unique structure, the hydrogel (abbreviated as AGC16/NTS) has the potential to be used as a multifunctional drug delivery system. The structure and properties of AGC16/NTS were characterized by rheological measurements, differential scanning calorimetry, variable-temperature 1H nuclear magnetic resonance, ultraviolet-visible spectroscopy, variable-temperature fluorescence emission spectroscopy, cryogenic scanning electron microscopy, transmission electron microscopy and X-ray diffraction methods...
January 15, 2018: Soft Matter
https://www.readbyqxmd.com/read/29334096/microwave-induced-covalent-functionalization-of-few-layer-graphene-with-arynes-under-solvent-free-conditions
#4
M V Sulleiro, S Quiroga, D Peña, D Pérez, E Guitián, A Criado, M Prato
A non-conventional modification of exfoliated few-layer graphene (FLG) with different arynes under microwave (MW) irradiation and solvent-free conditions is reported. The described approach allows reaching fast, efficient and mild covalent functionalization of FLG.
January 15, 2018: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/29334090/supramolecular-photosensitizers-rejuvenate-photodynamic-therapy
#5
Xingshu Li, Songyi Lee, Juyoung Yoon
Owing to its spatiotemporal selectivity and noninvasive nature, photodynamic therapy (PDT) has become a clinically promising approach for the treatment of a wide range of cancers and other diseases. However, the full potential of PDT has not been achieved thus far as a consequence of the lack of optimal photosensitizers (PSs) and/or smart transport/activation strategies. These problems, which unfortunately lie at the core of the PDT paradigm, include the oxygen reliance limits, the effect of PDT on hypoxic tumors, limitations of light penetration, and undesired skin photosensitization induced by "always on" PSs...
January 15, 2018: Chemical Society Reviews
https://www.readbyqxmd.com/read/29334089/asymmetric-4-2-annulations-to-construct-norcamphor-scaffolds-with-2-cyclopentenone-via-double-amine-thiol-catalysis
#6
Qian-Qian Yang, Wei Xiao, Wei Du, Qin Ouyang, Ying-Chun Chen
An efficient double catalytic system, combining chiral amine and 2-mercaptobenzoic acid, is applied for α',β-regioselective [4+2] annulations of 2-cyclopentenone with a diversity of activated alkenes, constructing multifunctional chiral bicycle[2,2,1]heptane scaffolds in good to excellent yields and enantioselectivities. In comparison with the traditional cross-dienamine species between 2-cyclopentenone and chiral amine, the interrupted enamine intermediate containing a covalently linked thiol catalyst shows significantly improved reactivity...
January 15, 2018: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/29334087/achiral-non-fluorescent-molecule-assisted-enhancement-of-circularly-polarized-luminescence-in-naphthalene-substituted-histidine-organogels
#7
Dian Niu, Lukang Ji, Guanghui Ouyang, Minghua Liu
A naphthalene substituted histidine derivative was found to form an organogel showing circularly polarized luminescence (CPL) and the addition of non-fluorescent achiral benzoic acids could efficiently enhance the CPL via non-covalent interactions.
January 15, 2018: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/29333698/design-of-enzyme-micelles-with-controllable-concavo-convex-micromorphologies-for-highly-enhanced-stability-and-catalytical-activity
#8
Tao Chen, Yuanhong Xu, Wenrong Yang, Aihua Li, Yao Wang, Jing Sun, Jingquan Liu
Concavo-convex micelles with controllable sizes and nanostructures are prepared via self-assembling polymer-enzyme (e.g., shellac enzyme) conjugates with heterogeneous polymer chains, which exhibit higher enzyme stability (300%) and bioactivity (760%) comparing with the well-defined ones. The applied amphiphilic and negatively charged copolymer, poly (methyl methacrylate)-block-poly (sodium p-styrene sulfonate), is synthesized via reversible addition-fragmentation chain transfer polymerization to modify shellac enzyme and immobilize the enzyme bioactivity inducer by covalent conjugation and electrostatic attraction, respectively...
January 15, 2018: Macromolecular Bioscience
https://www.readbyqxmd.com/read/29332832/electrochemiluminescent-detection-of-cardiac-troponin-i-by-using-soybean-peroxidase-labeled-antibody-as-signal-amplifier
#9
Min Tang, Zhenxian Zhou, Li Shangguan, Fang Zhao, Songqin Liu
This work proposed an electrochemiluminescence (ECL) immunosensor for quantitative monitoring of cardiac troponin I (cTnI) in plasma with soybean peroxidase (SBP) labeled-antibody as signal amplifier. The ECL sandwich immunosensor was constructed by covalent binding anti-cTnI capture antibody (Ab1) to polyethylenimine-functionalized graphene matrix, which was obtained by a simple hydrothermal reaction between polyethylenimine (PEI) and graphene oxide (GO). After that, the SBP-labeled detection antibody (SBP-Ab2), synthesized by NaIO4 method, was immobilized on the surface of electrode through sandwich immunoreaction...
April 1, 2018: Talanta
https://www.readbyqxmd.com/read/29330644/hydrocarbon-stapled-antimicrobial-peptides
#10
Dorian Migoń, Damian Neubauer, Wojciech Kamysz
Antimicrobial peptides are promising candidates for anti-infective pharmaceuticals. Unfortunately, because of their low proteolytic and chemical stability, their usage is generally narrowed down to topical formulations. Until now, numerous approaches to increase peptide stability have been proposed. One of them, peptide hydrocarbon stapling, a modification based on stabilizing peptide secondary structure with a side-chain covalent hydrocarbon bridge, have been successfully applied to many peptides. Moreover, constraining secondary structure of peptides have also been proven to increase their biological activity...
January 12, 2018: Protein Journal
https://www.readbyqxmd.com/read/29330603/magnetic-covalent-triazine-based-frameworks-as-magnetic-solid-phase-extraction-adsorbents-for-sensitive-determination-of-perfluorinated-compounds-in-environmental-water-samples
#11
Ji-Yun Ren, Xiao-Li Wang, Xiao-Li Li, Ming-Lin Wang, Ru-Song Zhao, Jin-Ming Lin
Covalent organic frameworks (COFs), which are a new type of carbonaceous polymeric material, have attracted great interest because of their large surface area and high chemical and thermal stability. However, to the best of our knowledge, no work has reported the use of magnetic COFs as adsorbents for magnetic solid-phase extraction (MSPE) to enrich and determine environmental pollutants. This work aims to investigate the feasibility of using covalent triazine-based framework (CTF)/Fe2O3 composites as MSPE adsorbents to enrich and analyze perfluorinated compounds (PFCs) at trace levels in water samples...
January 12, 2018: Analytical and Bioanalytical Chemistry
https://www.readbyqxmd.com/read/29330104/circular-rna-an-emerging-non-coding-rna-as-a-regulator-and-biomarker-in-cancer
#12
Bing Chen, Shenglin Huang
Circular RNA (circRNA) is a type of covalently closed non-coding RNA that may regulate gene expression in eukaryotes. The recent application of high-throughput RNA sequencing and bioinformatics approaches has revealed a large number of circRNAs in human cells. Emerging evidence indicates that many circRNAs have cell-type specific expression and are linked to physiological development and various diseases. Specially, circRNAs can either serve as oncogenic stimuli or tumor suppressors in cancer. circRNAs have also been shown to be enriched and stable in extracellular fluid, indicating the potential of circRNAs as cancer biomarkers...
January 9, 2018: Cancer Letters
https://www.readbyqxmd.com/read/29329073/nanobiostructure-of-fibrous-like-alumina-functionalized-with-an-analog-of-the-bp100-peptide-synthesis-characterization-and-biological-applications
#13
L M F C Torres, N A Braga, I P Gomes, M T Almeida, T L Santos, J P de Mesquita, L M da Silva, H R Martins, K C Kato, W T P Dos Santos, J M Resende, M C Pereira, M P Bemquerer, M A Rodrigues, R M Verly
The functionalization of alumina nanoparticles of specific morphology with antimicrobial peptides (AMP) can be a promising strategy for modeling medical devices and packaging materials for cosmetics, medicines or food, since the contamination by pathogens could be reduced. In this paper, we show the synthesis of a fibrous-like alumina nanobiostructure, as well as its functionalization with the peptide EAAA-BP100, an analog of the antimicrobial peptide BP100. The antibacterial activity of the obtained material against some bacterial strains is also investigated...
January 3, 2018: Colloids and Surfaces. B, Biointerfaces
https://www.readbyqxmd.com/read/29328669/urinary-methyleugenol-deoxyadenosine-adduct-as-potential-biomarker-of-methyleugenol-exposure-in-rats
#14
Yukun Feng, Saide Wang, Hui Wang, Ying Peng, Jiang Zheng
Methyleugenol (ME), a natural ingredient of several herbs and spices used in the human diet, is hepatocarcinogenic in rodents. Following metabolic activation to reactive carbocation intermediate, ME can bind covalently to DNA, which is directly associated with its carcinogenicity. In this work, a non-invasive approach to determine ME exposure was established by monitoring urinary ME-dA adduct. The developed method entails liquid-liquid extraction enrichment of the urinary ME-dA, incorporation of deuterated ME-dA as internal standard, and analysis by liquid chromatography coupled tandem mass spectrometry...
January 12, 2018: Journal of Agricultural and Food Chemistry
https://www.readbyqxmd.com/read/29328649/phenylthiomethyl-ketone-based-fragments-show-selective-and-irreversible-inhibition-of-enteroviral-3c-proteases
#15
Robert Schulz, Amira Atef, Daniel Becker, Franziska Gottschalk, Carolin Tauber, Stefan Wagner, Christoph Arkona, Atef A Abdel-Hafez, Hassan H Farag, Jörg Rademann, Gerhard Wolber
Lead structure discovery mainly focuses on the identification of noncovalently binding ligands. Covalent linkage, however, is an essential binding mechanism for a multitude of successfully marketed drugs although discovered by serendipity in most cases. We present a concept for the design of fragments covalently binding to proteases. Covalent linkage enables fragment binding unrelated to affinity to shallow protein binding sites and at the same time allows differentiated targeted hit verification and binding location verification through mass spectrometry...
January 12, 2018: Journal of Medicinal Chemistry
https://www.readbyqxmd.com/read/29327937/synthesis-structure-and-property-of-corona-6-arenes-and-their-assembly-with-anions-in-the-crystalline-state
#16
Meng-Yao Zhao, De-Xian Wang, Mei-Xiang Wang
The synthesis, conformational structure, electronic property and anion complexation of novel coronarenes were systematically studied. A number of corona[4]arene[2]tetrazines that contain different combinations of nitrogen atom with O, S, SO2 and CH2 as bridging units were synthesized conveniently by means of a fragment coupling strategy based on efficient nucleophilic aromatic substitution reaction of easily available aromatic dinucleophiles and 3,6-dichlorotetrazine. The resulting macrocycles adopt coronary conformational structures with the nitrogen bridge(s) forming conjugation with carbonyl and the other heteroatom linkages with tetrazine...
January 12, 2018: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/29327751/a-novel-covalent-post-synthetically-modified-mof-hybrid-as-a-sensitive-and-selective-fluorescent-probe-for-al3-detection-in-aqueous-media
#17
Shu-Yin Zhu, Bing Yan
A modified MOF named UiO-66-NH2-SA was synthesized based on the covalent post synthetic attachment of the MOFs (UiO-66-NH2) and salicylaldehyde via a Schiff-base reaction. The as-prepared functionalized UiO-66-NH2-SA not only maintains its structural integrity during the PSM process, but also shows excellent luminescence and good fluorescence stability in water. It was further utilized as a novel fluorescent probe for detecting of Al3+. The fluorescence intensity of UiO-66-NH2-SA increased linearly upon increasing the concentration of Al3+ in the range of 0-500 μM with a detection limit of 6...
January 12, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/29327511/cp2tix-complexes-for-sustainable-catalysis-in-single-electron-steps
#18
Andreas Gansäuer, Ruben Benedikt Richrath, Theresa Olyschläger, Sven Hildebrandt, Daniel G Enny, Godfred D Fianu, Robert A Flowers Ii
We present a combined electrochemical, kinetic, and synthetic study with a novel and easily accessible class of titanocene catalysts for catalysis in single electron steps. The tailoring of the electronic properties of our Cp2TiX-catalysts that are prepared in situ from readily available Cp2TiX2 is achieved by varying the anionic ligand X. Of the complexes investigated, Cp2TiOMs proved to be either equal or substantially superior to the best catalysts developed earlier. The kinetic and thermodynamic properties pertinent to catalysis have been determined...
January 11, 2018: Chemistry: a European Journal
https://www.readbyqxmd.com/read/29327308/methionine-in-proteins-it-s-not-just-for-protein-initiation-anymore
#19
Jung Mi Lim, Geumsoo Kim, Rodney L Levine
Methionine in proteins is often thought to be a generic hydrophobic residue, functionally replaceable with another hydrophobic residue such as valine or leucine. This is not the case, and the reason is that methionine contains sulfur that confers special properties on methionine. The sulfur can be oxidized, converting methionine to methionine sulfoxide, and ubiquitous methionine sulfoxide reductases can reduce the sulfoxide back to methionine. This redox cycle enables methionine residues to provide a catalytically efficient antioxidant defense by reacting with oxidizing species...
January 11, 2018: Neurochemical Research
https://www.readbyqxmd.com/read/29327259/5-aminolevulinic-acid-squalene-nanoassemblies-for-tumor-photodetection-and-therapy-in-vitro-studies
#20
Andrej Babič, V Herceg, E Bastien, H-P Lassalle, L Bezdetnaya, Norbert Lange
Protoporphyrin IX (PpIX) as natural photosensitizer derived from administration of 5-aminolevulinic acid (5-ALA) has found clinical use for photodiagnosis and photodynamic therapy of several cancers. However, broader use of 5-ALA in oncology is hampered by its charge and polarity that result in its reduced capacity for passing biological barriers and reaching the tumor tissue. Advanced drug delivery platforms are needed to improve the biodistribution of 5-ALA. Here, we report a new approach for the delivery of 5-ALA...
January 11, 2018: Nanoscale Research Letters
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